1. Field of the Invention
The present invention relates to a system and apparatus for detecting and reporting a movable body by using electromagnetic wave or radio communication.
2. Description of Related Art
A variety of conventional methods for detecting another approaching vehicle or another approaching movable body while the driver is driving a vehicle have been proposed so far.
For example, according to a method disclosed in Japanese Patent Laid-open No. Hei 2-216600, a vehicle is running while a receiver provided in the vehicle is monitoring incoming signals. Furthermore, a warning wave transmitted by a transmitter is installed on another movable body which is received by the receiver. A warning is then generated to notify the driver of the existence of the other movable body.
However, the number of movable bodies causing a warning is not known. Thus, in some cases, the existence of only one vehicle can be confirmed by the sense of eight or more vehicles. Therefore, it is difficult to verify the existence of other vehicles.
In order to solve this problem, there has been proposed a method as disclosed in Japanese Patent Laid-open No. Hei 7-225274. With this method, it is possible to determine whether only one movable body or a plurality of movable bodies exist within a predetermined distance by comparing an interval between rising edges of two consecutive pulses of a received signal and to display a result of the determination.
However, a moveable body detected may disappear from detection temporarily behind an obstruction such as another large-sized vehicle or a fence before appearing again.
In this case, when the movable body disappears behind the obstruction, the warning wave transmitted thereby can no longer be received, causing a warning generated by the wave to be halted. Thus, the driver may forget the existence of the movable body, being no longer alert.
In such a case, when the movable body disappearing from detection temporarily appears again, the movable body which no longer receives attention does reappear, generating a warning wave. As a result, the driver gets bewildered.
It is also difficult for the driver to immediately determine whether a warning is generated from a warning wave transmitted by a reappearing movable body or newly transmitted by another movable body.
By merely knowing the number of other movable bodies; however, the existence of a plurality of movable bodies still raises a problem in that when 2 or more vehicles can be verified by the sense of sight, it is quite within the bounds of possibility that another hidden vehicle still exists.
That is to say, it is impossible to form a judgment as to whether or not a vehicle exists behind an obstruction with a high degree of reliability.
It is thus an object of the present invention addressing the problem described above to provide a movable body detecting/notifying system that is capable of determining and reporting whether another movable body exists behind an obstruction or at a position that can be verified by the sense of sight.
In order to achieve the object of the present invention described above, according to a first embodiment of the present invention, a movable body detecting/notifying system allows a detecting movable body to detect and report a detected movable body by using electromagnetic wave communication. The detected movable body transmits a large-wavelength electromagnetic wave which is easily diffractable by an obstruction as well as a small-wavelength electromagnetic wave which is not easily diffractable by an obstruction at the same time. The detecting movable body generates a notice for reception of only the large-wavelength electromagnetic wave without the small-wavelength electromagnetic wave or a notice for reception of both the large-wavelength and small-wavelength electromagnetic waves which is different from the notice for reception of only the large-wavelength electromagnetic wave.
The reception of only the large-wavelength electromagnetic wave by the detecting movable body indicates that the small-wavelength electromagnetic wave is hindered by an obstruction and that the detected movable body is hidden under the shadow of the obstruction and the existence of the detected movable body can not be confirmed by the sense of sight. On the other hand, the reception of both the large-wavelength and small-wavelength electromagnetic waves by the detecting movable body indicates that the detected movable body is not hidden under the shadow of an obstruction and exists at a position that can be verified even by the sense of sight.
By generating notices different from each other for the two cases described above, the driver of the detecting movable body is capable of knowing whether another movable body is hidden by an obstruction or exists at a position that can be verified by the sense of eight.
Thus, the notice of the existence of another movable body behind an obstruction can be regarded as preparatory information which urges an action such as suspension of acceleration or a braking operation of the vehicle. On the other hand, the notice of the existence of another movable body at a position verifiable by the sense of sight is judged to be a warning which urges a deceleration or a halt of the vehicle.
According to a second aspect of the first embodiment of the present invention, a movable body detecting/notifying system allows a detecting movable body to detect and report a detected movable body by using electromagnetic wave communication with the movable body detecting/notifying system. The detected movable body transmits a small-wavelength electromagnetic wave which is not easily diffractable by an obstruction. A repeater receives the small-wavelength electromagnetic wave and adds a relay code and relays the small-wavelength electromagnetic wave in a particular direction. When the detecting movable body receives the small-wavelength electromagnetic wave, the detecting movable body determines whether or not a relay code has been added to the small-wavelength electromagnetic wave. Furthermore, the detecting movable body generates a notice for reception of a small-wavelength electromagnetic wave with no relay code added thereto or a notice for reception of a small-wavelength electromagnetic wave with a relay code added thereto different from the notice for reception of the small-wavelength electromagnetic wave with no relay code added thereto.
The reception of only the small-wavelength electromagnetic wave with a relay code added thereto can be judged to indicate that the detected movable body is hidden by an obstruction while reception of a small-wavelength electromagnetic wave with no relay code added thereto can be judged to indicate that the existence of the detected movable body can be verified by the sense of sight.
By generating notices different from each other for the two cases described above, the driver of the detecting movable body is capable of determining whether another movable body is hidden by an obstruction or exists at a position that can be verified by the sense of sight.
According to a third aspect of the first embodiment of the present invention, a movable body detecting/notifying system allows a detecting movable body to detect and report a detected movable body by using electromagnetic wave communication with the movable body detecting notifying system. The detecting movable body receives information on a position of the detected movable body from a traffic regulating center for grasping information on positions of movable bodies in a predetermined range. The detected movable body transmits a small-wavelength electromagnetic wave which is not easily diffractable by an obstruction. When the information on a position of the detected movable body proves that the detected movable body is moving in a particular direction, the detecting movable body generates a notice for reception of no small-wavelength electromagnetic wave or a notice for reception of the small-wavelength electromagnetic wave different from the notice for reception of no small-wavelength electromagnetic wave.
After the information on a position of the detected movable body received from the traffic regulating center indicates the existence of the detected movable body, reception of no small-wavelength electromagnetic wave can be judged to indicate that the detected movable body is hidden by an obstruction while reception of the small-wavelength electromagnetic wave can be judged to indicate that the existence of the detected movable body can be verified by the sense of sight.
By generating notices different from each other for the two cases described above, the driver of the detecting movable body is capable of determining whether another movable body is hidden by an obstruction or exists at a position that can be verified by the sense of sight.
According to a fourth aspect of the first embodiment of the present invention, a movable body detecting/notifying system allows a detecting movable body to detect and report a detected movable body by using electromagnetic wave communication with the movable body detecting/notifying system. The detected movable body transmits an electromagnetic wave. The detecting movable body receives the electromagnetic wave. Furthermore, the detecting movable body generates notices different from each other before and after a large change in detected intensity of the electromagnetic wave.
A low detected intensity of a received electromagnetic wave can be judged to indicate that the electromagnetic wave has been diffracted by an obstruction, by which the detected movable body is hidden. On the other hand, an increasing detected intensity can be judged to indicate that the detected movable body appears from a state hidden by an obstruction, with the position of the detected movable body becoming verifiable by the sense of sight.
By generating notices different from each other before and after a large change in detected intensity of an electromagnetic wave, the driver of the detecting movable body is capable of determining whether another movable body is hidden by an obstruction or exists at a position that can be verified by the sense of sight.
According to a fifth aspect of the first embodiment of the present invention, a movable body detecting/notifying system includes an ID code identifying a movable body added to an electromagnetic wave generated by the movable body. By adding an ID code to an electromagnetic wave, it becomes possible to determine whether each of a plurality of other detected movable bodies is hidden by an obstruction or exists at a position that can be verified by the sense of sight from different notices.
It is another object of the present invention addressing the problem described above to provide a movable body detecting/notifying apparatus that is capable of warning a driver of the fact that another movable body has disappeared from detection temporarily behind an obstruction in order to keep the driver alert.
In order to achieve the object described above, a second embodiment of the present invention provides a movable body detecting/notifying apparatus which includes a receiving means for receiving an electromagnetic wave transmitted by another movable body, a pattern analyzing means for analyzing a variable pattern of a detected intensity of an electromagnetic wave received by the receiving means, a pattern storing means for storing a variable pattern of a detected intensity of an electromagnetic wave which is received by the receiving means when a movable body transmitting the electromagnetic wave disappears from detection behind an obstruction, a pattern-approximation determining means for comparing a variable pattern of a detected intensity of an electromagnetic wave analyzed by the pattern analyzing means with a variable pattern of a detected intensity of an electromagnetic wave stored in the pattern storing means in order to determine whether or not the variable pattern analyzed by the pattern analyzing means is approximate to the variable pattern stored in the pattern storing means, and a notification control means for controlling a notification means on the basis of a result of determination output by the pattern-approximation determining means.
The movable body detecting/notifying apparatus is characterized in that the notification control means drives the notification means to output a warning notification urging a caution when a result of determination produced by the pattern-approximation determining means indicates that a variable pattern of a detected intensity of an electromagnetic wave analyzed by the pattern analyzing means is approximate to a variable pattern of a detected intensity of an electromagnetic wave stored in the pattern storing means and stops a warning notification when the detected intensity of the electromagnetic wave is restored.
When a variable pattern of a detected intensity of an electromagnetic wave generated by another movable body is judged to be approximate to a variable pattern of a detected intensity of an electromagnetic wave which was obtained when the other movable body disappeared from detection and stored in advance in the pattern storing means, the other movable body is judged to disappear from detection temporarily and a warning is given to the driver. Thus, the driver is always made aware of the existence of the other movable body and is alert so that the driver will not get bewildered by the reappearance of the other movable body.
According to a second aspect of the second embodiment of the present invention, a movable body detecting/notifying apparatus, the notification control means halts a warning notification of the notification means after the warning notification has been continuing for a predetermined period of time.
Even when a warning notification is output after a movable body is determined to temporarily disappear from detection behind an obstruction, the disappearance is not always temporary. In such a case, the movable body may have gone to a by-road and never appears again. Thus, the warning notification is halted after a predetermined period of time has lapsed, preventing the warning notification from being continued.
According to a third aspect of the second embodiment of the present invention, a movable body detecting/notifying apparatus includes a pattern-approximation determining means which has a frequency determining means for determining whether or not a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means frequently, i.e., whether or not the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means in a predetermined short period of time is large. If a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means frequently, i.e., if the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means in a predetermined short period of time is large, a sensitivity of the receiving mesas is reduced.
If a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means frequently, i.e., if the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means in a predetermined short period of time is large, a warning notification urging a caution will be repeated frequently, adversely causing awareness of the warning notification to be lost. In such a case, the sensitivity of the receiving means is reduced to decrease the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means.
According to a fourth aspect of the second embodiment of the present invention, a movable body detecting/notifying apparatus includes a pattern-approximation determining means which has a frequency determining means for determining whether or not a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means frequently, i.e., whether or not the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means in a predetermined short period of time is large. If a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means frequently, i.e., if the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means in a predetermined short period of time is large, a threshold value used by the notification control means as a criterion as to whether or not a detected intensity of an electromagnetic wave has been recovered is increased.
If a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means frequently, i.e., if the number of times a variable pattern analyzed by the pattern analyzing means is judged to be approximate to a variable pattern stored in the pattern storing means in a predetermined short period of time is large, a threshold value used by the notification control means as a criterion as to whether or not a detected intensity of an electromagnetic wave has been recovered is increased so as to prevent the warning notification urging a caution from being repeated.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.